The Chronic Effects of Neurotrauma Consortium (CENC; W81XWH-13-2-0095) has been a highly productive, coordinated, multicenter, basic science-to-bedside, research collaboration led by VCU/VA researcher David Cifu, MD and jointly funded since 2013 by the DoD and VA. CENC linked basic, translational, epidemiologic, and clinical neuroscience researchers from the VA, military, academia, and private sector to effectively address the diagnostic challenges and therapeutic ramifications of mild traumatic brain injury (mTBI) and its potential long-term effects. Experienced and proven researchers from the CENC comprise the LIMBIC team at the level of Consortium Leadership, Core Facility, and Research Study Directors. This proven team of leaders, infrastructure supporters and researchers will initiate targeted, expanded research studies that extend CENC research findings, address all priorities (required and secondary research elements) detailed in the program announcement, and will produce deliverables for the clinicians in the field. The four infrastructure Cores (Biomarkers, Neuroimaging, Data and Biostatistics, Clinical Studies) will work in concert to accomplish three overarching, interrelated aims: Aim 1. Transition and expand CENC to LIMBIC -- Enroll and expand sizes of relevant cohorts of Veterans and Servicemembers; expand data points collected; collect data in accordance with established guidelines; and identify and describe key characteristics of populations to guide rigorous studies on the nature and degree of mTBI late effects in combat Vs/SMs over time. Aim 2. Comorbidities & Neurologic sequela -- Determine prevalence and associations of mTBI with important comorbidities and neurologic sequela, such as dementia and neurodegenerative disease, pain, psychological health including PTSD, and neurosensory deficits. Determine nature and degree of mTBI late effects over time. Aim 3. Phenotypes -- Identify characteristics (e.g., repetitive mTBI, deployment-only mTBI, frequent low level blast or other subconconcussive head/brain impact exposure, baseline neurocognitive deficits, presence of neurologic signs, presence of symptoms), pathophysiology, biomarkers, and subpopulations (e.g., women) that serve as risk or protective factors for long-term outcomes such as neurodegeneration, symptom burden and health economics. LIMBIC will continue the mission begun by CENC, which has the Veterans, Service Members, and their family members at the center of the work performed, to develop, deploy, and disseminate patient-centered health care tools and strategies. Work conducted to-date has expanded knowledge in the areas of chronic pain, sleep, sensory disorders, psychological health, and return to work. Knowledge translation underway includes improving both care and systems of care to the population, translatable to both military and the general public populations. We are poised to achieve LIMBIC?s intent to ?improve acute TBI care and subsequent support systems for chronic care following mTBI?.